After the Import screen popped up select the source of the import: Files / Photos / Camera

Controlling your imported images

Right after the import

Your image will be imported in relation to your current view, in case you need to position it, it will be shown selected, with the handlebar attached to it. Use the various arrows on the handlebar to position the image, same way as you've learned it in Move/Rotate/Scale. You will also have the option to set the opacity of the image.

After you are finished, tap on Done.

Later, during modeling

After the import process, you will be able to access your images

from the Groups menu, where you can delete them, set their opacity and make the invisible.

from Transform > Move, Rotate, Scale or Transform > Translate, where you can reposition them